Fulton County, created from DeKalb County in 1853, spread out in its strange, elongated shape by absorbing the counties of Milton (to the north) and Campbell (to the south) during the Great Depression. It is named for Robert Fulton, inventor of the steam-driven boat.

Atlanta, the county seat and state capital, flourished as the terminal point on an early railroad; fittingly, residents initially called the city Terminus. Later, residents changed the city's name to Marthasville as a compliment to Governor Wilson Lumpkin's daughter.